Ministeria vibrans (strain Tong 1997, ATCC #50519) is a close unicellular relative of animals that under typical mixed culture conditions does not exhibit multicellularity. However, we found that when M. vibrans is grown in monoxenic culture with the alphaproteobacterium Thalassospira lucentensis, the dominant bacterium in the mixed culture, it undergoes aggregative multicellularity. We performed RNA-sequencing of M. vibrans monoxenic cultures with T. lucentensis during the aggregation process to investigate associated gene expression patterns. Six timepoints were taken, with four replicates each: 12 hr and 18hr (prior to aggregate formation), 24hr and 33hr (during aggregate formation), and 48hr and 72hr (during aggregate maturation).